Tension device for sewing-machines



(No Model.)

D. L. KEELER.

TENSION DEVICE FOR SEWING MACHINES.

No. 328,688. Patented 001;. 20, 1885.

WITNESSES: g INVENTOR W 0 1/6 ATTORNEY N PUERS. PhaQo-Lilhograpimr, Wnhingmn. D. c.

DAVID L. KEELER, OF GRAND RAPIDS, MICHIGAN.

TENSION DEVICE FOR SEWING-MACHINES.

BPECIPICATION forming part of Letters Patent No. 328,688, dated October 20, 1885.

Application filed September 19,1884. Serial No. 143,507. (No model.)

To all whom it may concern:

Be it known that 1, DAVID L. KEELER,a citizen of the United States, residing at the city of Grand Rapids, in the county of Kent and State of Michigan, have invented certain new and useful Improvements in Tension Devices for Sewing-Machines; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

This invention relates to tension devices for sewing-machines; and it consists, in addition to an ordinary tension, in an automatic tension and mechanism for releasing the same.

The invention is illustrated in the accompa nying drawings, in which Figure 1 is a vertical longitudinal section of the upper portion of the head of a sewing-machine, showing my improved tension devices. Fig. 2 is a vertical transverse section of the same. Fig. 3 is a sectional view of the upper part of the same device shown in Fig. l, on an enlarged scale, and showing a slight modification.

Like letters designate corresponding parts in all of the figures.

A is the head of a sewing-machine, in which my improved tension devices are mounted. The tension-bar B, which extends through the top plate of the head A, is made of two sepa rate parts, a and b. The upper part, a, may be simply fitted into the lower part, b, as in Fig. 1, or it may be screwed therein, as in Fig. 3. In either case the two parts are adjusted to their correct relative positions by means of the setscrew 0. The upper part, a, of the tension-bar is formed with a flange, (1, upon which rest the tension-disks O G, which constitute the ordinary tension device. The tension of these disks is given by a coiled spring, 0, encircling the tension-bar, the tension being regulated by a thumbnut, f, which screws onto the upper end of the tension-bar.

Beneath the flange (l, and resting upon the head A, is another set of tension-disks, D D, which constitute the automatic tensiondisks of my invention. Tension is given to these disks by means of a coiled spring, 9, which encircles the lower part, b, of the tension-bar within the head A. This spring bears against the lower surface of the upper plate of the head A, and

against a shoulder, h, formed on the tensionbar. The tension of this spring is regulated by means of adjusting the two parts a and b of the tension-bar vertically in relation to each other.

For automatically releasingthe tension of the disks D D, I adopt the following mechanism: The lower part, b, of the tension-bar B is bent so as to form a foot, the heelz' of which rests on an eccentric, E, formed on ashaft, G, which shaft is the main operating-shaft of the sewing-machine. The end m of the foot is attached to the head A by means of a screw or bolt, a, which bolt passes through an elongated slot, 0, in the end m, to allow the tension-bar to rise and fall without binding. As the shaft G rotates, the eccentric E causes the tensionbar. 13 to rise and fall, andwhen it raises the tension-bar it relieves the tension of the disks D D and releases the thread. The spring in addition to giving tension to the disks D D, insures the heel ibeing at all times in con tact with the eccentric E, and the vertical adjustment of the two parts of the tension-bar in relation to each other permits the wear between the heel of the tension-bar and the eccentric to be taken up.

Formed on one of the tension-disks, preferably the upper one of the set C O, is a lip, S, which serves as a guard to keep the thread from slipping out between the disks.

The two sets of tension-disks are used separately, and the ordinary tension-disks are provided for cases where it might not be desirable to use the automatic tension-disks.

It is obvious that the flange d on the tensionbar might be omitted, and the upper disk of the set D might be rigidly secured to the bar instead, and I do not confine myself to the speo cific devices shown for operating the tensionbar from the shaft G.

I claim as my invention- 1. A tension -bar having a flange formed thereon,a set of tension-disks above said flange, 5 and means for giving tension thereto, in combination with a set of tension-disks below said flange, mechanism which normally holds said flange pressed against said lower disks, thus giving tension thereto, and mechanism which automatically raises and lowers said tensionbar, whereby the tension on said lower disks is released and applied without the tension on the upper disks being afiected, substantially as set forth. a

2. The sewing-machine head A, the tensionbar B, having flanges d and h, and mechanism which automatically raises and lowers said bar, in combination with the tension-disks G 0 above the flange d, the tension-disks D D be- -1ow said flange, and the springs e and subencircling bar B above disks 0 G, adjustingnut f on the end of bar B, against which bears spring 6, tension-disks D D, surrounding bar B between head A and flange d, and spring g, encircling bar B between head A and flange h, substantially as set forth.

4. Tension-bar B, provided with flange d, and composed of two parts, a and b, and mechanism which automatically raises and lowers said bar, in combination with disks D D, spring 9, and set-screw a, substantially as set forth.

In testimony whereof I affix my signature in presence of two witnesses.

- DAVID L. KEELER.

Witnesses:

FRED W. STEVENS, ARTHUR O. DENISON. 

